1. Field of the Invention
The present invention relates to an integrated circuit which provides a reliability-testing function such as a burn-in operation.
2. Description of the Related Art
The inventors of the present invention know that a burn-in test of an integrated circuit is performed in order to selectively remove an initial defective circuit item after manufacture.
The inventors know an integrated circuit test which is intended to bring the integrated circuit into a predetermined operating state and to make an unstable component of the integrated circuit obvious for removal in intensified conditions. This test thus makes a contribution to enhancing the reliability of the integrated circuit.
For the above-mentioned test, it is requested that the integrated circuit is connected to not only a d.c. (direct current) power supply but also a start signal source and a clock signal source, as well.
A supply voltage of the d.c. power supply is applied between a V.sub.DD terminal and a GND (Ground) terminal. A start signal of the start signal source is applied between a start input terminal and the GND terminal. A clock signal of the clock signal source is applied between a clock input terminal and the GND terminal.
By providing the start signal, the integrated circuit operates in a predetermined manner as being synchronized with the clock signal. When performing the burn-in test, in response to a test signal supplied to a start signal source, the integrated circuit is allowed to iteratively perform a series of predetermined testing operations. The integrated circuit provides lots of I/O (input/output) terminals including the terminals mentioned above. A testing signal may be often applied to the other terminals except them. Further, such a burn-in test is required to be performed about a relatively large number of integrated circuit items at a time. It means that the start signal source and the clock signal source have to supply signals to a large number of integrated circuits at a time. In a case that another input signal is needed, it is necessary to provide another signal source.
In the known burn-in test for an integrated circuit, as mentioned above, several kinds of signals are required to be supplied to the input terminals provided in the integrated circuit. When performing the burn-in test, since the test is conditioned at a high temperature and for a constant time, the integrated circuit is accommodated in a thermostatic chamber. The d.c. power supply and the other signal sources are located out of the thermostatic chamber so that those sources may be connected to the integrated circuit through conductive lines.
For connecting the integrated circuit to those conductive lines leading to sources, it is necessary to take a very troublesome operation.